1. Field of the Invention
This invention relates to a new differential pressure transmitter that comprises a linear air velocity transmitter and to a pneumatically operated square root extractor device for such a transmitter or the like as well as to methods of making such a transmitter and/or such a square root extractor device.
2. Prior Art Statement
It is known to provide a differential pressure transmitter comprising means for producing an output pneumatic signal from a pneumatic source in relation to the air velocity pressure of air flowing in a passage, means that senses the difference between the total pressure and the static pressure of the air flowing in the passage, and means for extracting the square root of the air velocity pressure of the air from the pneumatic output signal as the pneumatic output signal is being produced so that the pneumatic output signal is substantially linear with respect to the air velocity of the air flow in the passage whereby the transmitter comprises a linear air velocity transmitter. For example, see the U.S. Pat. No. 4,384,492 to Kreuter .